The present invention relates to a humidifier-injector for a jet ventilator.
Jet ventilators, and in particular high frequency jet ventilators, operate by introducing into the airway of a patient, a relatively small volume of gas on the order of 100 ml at a high velocity by way of a short pulse of, for example, 130 ms. This high speed stream will entrain and accelerate a larger volume of stationary gas through the open airway. The pulse duty cycle of approximately 33% on the 66% off is repeated up to several hundred times per minute resulting in a relatively large flow per minute in and out of the lungs, i.e., 18-30 LPM.
This high frequency low volume method of ventilation is insensitive to leaks or openings in the airway and does not result in the generation of high airway pressures as does conventional high volume low frequency ventilation. Clinical experience has shown that both the jet gas and the entrained gas must be humidified to prevent dessication of and damage to the mucosal lining of the airways.
Prior art high frequency jet ventilation systems have effected humidification of the high speed gas stream by conditioning the jet gas before injection, however this has the disadvantage of increasing the device comlexity.